It is known that such air intake arrangements are widely used in the aeronautic field with air refreshing purposes in an enclosed area containing heat sensitive materials and/or dangerous surroundings, of the flammable or explosive type, for which it is required to provide a continuous ventilation of the area so as to avoid any risk of malfunction of the materials or of surrounding incident.
This is more specifically the case of numerous mechanical and/or electrical devices provided in the annular enclosed area between the pod and the external case of the blower and compressors of an aircraft turbojet. Such devices, such as for example, the fadec (full authority digital control), the accessory gearbox, the engine oil tank, the fluid components, etc. generally fastened around the external case and thus located in the enclosed area, are ventilated by external air coming into the arrangement through the air intake hole for crossing the channel arranged in the pod and spreading, at the channel outlet, in the enclosed area. The devices, as well as the oil vapours or similar spreading out of this area, are ventilated with the external fresh air spread through the air channel, helping to ensure the good operation thereof.
In order to comply with the regulation in force, prescribing the air to be appropriately refreshed by time unit in the relevant enclosed area, the air passage channel of the arrangement has a predetermined cross-section allowing a sufficient amount of air to be circulated in the channel so as to provide, at the outlet thereof, the air refreshment in the enclosed area containing the devices to be ventilated.
However, as the amount of external air coming into the predetermined cross-section air channel is more specifically a function of parameters related to the speed of the aircraft and to the altitude thereof, it is difficult to optimally ventilate the devices to be cooled down and the vapours to be discharged.
Indeed, while the external air coming upstream through the air intake hole in the predetermined cross-section channel of the arrangement and coming out downstream the latter is sufficient for correctly ventilating the devices when the aircraft is in a ground taxiing phase or in a takeoff phase or even in a waiting phase, thus at a low speed and altitude, in contrast, when the aircraft is in a cruising flight phase at maximum speed and altitude, the air flow rate coming out of the channel of the arrangement towards the area to be ventilated is too significant. Measurements enabled to observe that, in such a flight phase, the air circulating in the enclosed area through the channel of the arrangement was refreshed twice as much as necessary. Furthermore, the air coming into the enclosed area generates drags, resulting in a speed loss for the aircraft, and thus in an increase of the fuel consumption for said engine.
In order to overcome such drawbacks, documents WO-2006/067296 and WO-2006/067299 describe air intake arrangements comprising plugging means with controllable mobile member, being associated with said air passage channel, and means for controlling said mobile member, operated either voluntarily by the pilot of said aircraft, or, advantageously, in an automatic way. In this latter case, said controlling means comprise a variable volume tank cylinder/piston, bladder, bellows, etc. assembly receiving the total pressure exerted on said aircraft by the air and being connected to said controllable mobile member. However, as the pressure is not locally stable, such a system cannot be optimum. In addition, such controlling means are heavy with respect to their environment and they tend to generate vibration or unbalance phenomena requiring some reinforcement of the assembly, which makes said air intake arrangement considerably heavier. Now, in order to restrict the fuel consumption of aircraft, the designers aim at creating lighter systems.
Thus, in order to overcome such drawbacks, document FR 07/02956 discloses an air intake arrangement comprising plugging means with controllable resilient blade, associated with said air passage channel, and means for controlling the resilient blade formed by an aerodynamic profile arranged transversally with respect to said air passage channel and fastened to an end of said resilient blade and able to generate a bearing strength under the action of the external air flow crossing the channel. However, micro-cracks are able to appear on the profile structure, including at the level of its fastening with the resilient blade, essentially as a result of the high speed of the air flow and of the high pressure applied on the profile, which may result in the life duration and the efficiency of said arrangement becoming considerably reduced.
The object of the present invention is to overcome such drawbacks and it relates to an air intake arrangement with a design allowing to provide an optimum ventilation of an enclosed area such as previously described regarding a turbojet, but that could also be a light area or a belly fairing of the aircraft or, generally, any more or less closed and heat sensitive area of an aircraft for which an air refreshment is desired.